Answer 1

You have to use bin() function. Its arguments have to be integers, so you have to convert your string first.

For example:
b = '256'
print(bin(int(b)))

>>>
0b100000000

where bin() returns a string again, which is a binary representation of the integer.

---

If you want to convert the other way round, it is a bit simpler. You just use int(x, y) where x is a binary string representation and y is the base of the number (in this case 2):

print(int('1000', 2))

>>>
8

This time a base10 integer is returned.

Answer 2

You mean to convert, let's say "8192" into 10000000000 and back?